This application claims the benefits of Japanese Application No. 11-232796 which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a oneway clutch to be assembled in an automatic transmission, or the like, of a car, and to the technology for facilitating a conveying work.
2. Related Background Art
Generally, an automatic transmission for a car comprises a planetary gear transmission mechanism capable of 3 to 5 speed changes, in addition to a torque converter serving as a fluid coupling, so as to conduct the speed change by properly fixing or releasing the constituent elements of the planetary gear transmission mechanism (a sun gear, a planetary gear, etc.) with frictional engagement means such as a clutch or a brake. As the frictional engagement means to be assembled in the automatic transmission, a wet-type multi-disc type means which comprises friction plates and separator plates alternately provided therein is employed, with the exception of certain band-type brakes. For the pressure engagement (frictional engagement) of the both plates, pressure oil from a gear change control oil pressure circuit is employed. Some of such frictional engagement means incorporate a oneway clutch therein, so as to freely rotate a gear shaft, or the like, in one direction, thereby realizing easier gear change control.
FIG. 6 is a front view for showing a conventional oneway clutch to be assembled in the frictional engagement means. FIG. 7 is a view for showing the portion D in FIG. 6 in an enlarged manner, and FIG. 8 is a cross-sectional view taken along the line Exe2x80x94E in FIG. 7.
This oneway clutch 1 comprises a cylindrical inner race (an output shaft, an input shaft, or the like, of the automatic transmission) 3, an annular outer race 5 provided to be coaxial and rotatable relatively with the inner race 3, a large number of rollers 7 interposed between the inner race 3 and the outer race 5 to serve as torque transmitting members, etc. On the inner peripheral surface of the outer race 5, there are formed a plurality of concave cams 13 formed along the circumferential direction and each comprising a trough 9 and an inclined surface 11, and a plurality of grooves 15 formed along the axial direction. Each of the rollers 7 is provided between the outer peripheral surface of the inner race 3 and the concave cam 13, and is biased to the inclined surface 11 inside the concave cam by means of a coil spring 17. The outer end portion 21 of each of the block bearings 19 made of oil impregnated sintered alloy is engaged with each groove 15, and a gap between the inner race 3 and the outer race 5 is maintained by these block bearings 19. In the drawings, a reference numeral 22 denotes a latch nail which is formed on the outer periphery of the outer race 5, to be engaged with a latch groove formed on the inner peripheral surface of an unrepresented gear element.
Attached to the outer race 5 is a retainer 23 which is made of synthetic resin and comprises a first annular flange 25 having a large diameter and a second annular flange 27 having a small diameter coupled to each other by means of first to third columns 29, 31 and 33. This retainer 23 is adapted to prevent separation or falling off of the rollers 7, the coil springs 17 or the block bearings 19. For example, the roller 7 and the coil spring 17 are interposed and retained between the columns 29, 31 and 33, while the block bearing 19 is between the second column 31 and the third column 33. In the drawings, a referential numeral 35 denotes a lip portion formed on the second column 31 and is engaged with a protrusion 37 which is formed on the outer end side of the block bearing 19.
In the conventional oneway clutch, the block bearing often falls off when it is being conveyed as a sub-assembly, so that a loss in time may be generated because of a re-assembling in an assembly line, etc., of the automatic transmission.
More specifically, in the aforementioned oneway clutch 1, since the inner race 3, which is a constituent element, is the output shaft, or the input shaft, or the like, of the automatic transmission, the inner race 3 naturally does not exist in a sub-assembly 39 prior to the assembly of the automatic transmission. Accordingly, if any impact is given in the course of conveyance of the sub-assembly 39, the lip portion 35 of the second column 31 is elastically deformed, whereby the block bearing 19 falls off comparatively easily. In this case, an assembler is supposed to pick up the fallen-off block bearing 19 to be assembled again, which work, however, is an irregular work that may cause deceleration of the conveyer speed of the assembly line. Also, if the fallen-off block bearing 19 rolls into a lower part of the conveyer, or the like, the assembly line may be suspended under certain circumstances.
Taking the aforementioned circumstances into consideration, an object of the present invention is to provide a oneway clutch which allows a retainer to securely retain a block bearing so as to enhance the efficiency in the assembling work.
In order to solve the above problems, according to the present invention, there is proposed a oneway clutch which comprises an inner race, an outer race provided coaxial and relatively rotatable with the inner race, a plurality of concave cams, each consisting of a trough and an inclined surface, formed on the inner peripheral surface of the outer race along the circumferential direction thereof, a plurality of grooves formed on the inner peripheral surface of the outer race along the axial direction thereof, a plurality of torque transmitting members interposed between the outer peripheral surface of the inner race and the concave cams, biasing means for biasing these torque transmitting members toward the inclined surface side in the concave cam, block bearings to be engaged with the grooves and adapted to maintain a gap between the inner race and the outer race, and a retainer attached to the outer race so as to retain the torque transmitting members, the biasing means and the block bearings, and wherein the torque transmitting members roll from the trough side to the inclined surface side only at the time of one directional relative rotation of the inner race and the outer race so as to conduct a torque transmission, and each of the block bearings comprises a latch recess formed on a side surface thereof or a latch hole extended through in the axial direction, while the retainer is provided with the latch recess or a latch protrusion to be fitted in the latch hole.
According to this invention, when the block bearing is thrust into a predetermined part of the retainer, the retainer is elastically deformed and the latch protrusion is fitted in the latch recess or the latch hole of the block bearing, so that the block bearing does not easily fall off.
Also, according to the invention, it is preferable, in the oneway clutch set forth above, that the retainer is made of synthetic resin. According to this feature, the retainer and the oneway clutch may be light-weighted, and at the same time, the retainer may be easily deformable elastically when the block bearing is assembled.
Also, according to the invention, it is preferable, in the oneway clutch set forth above, that the latch protrusion is adapted to bias the block bearings to the inner peripheral surface of the outer race. According to this feature, the block bearing is not moved to the inner race side in the course of conveyance, so that the inner race and the block bearing do not interfere with each other during the assembly.